New methods for installation of tubular structures in well have recently been introduced like mono-diameter/mono-bore casing systems but have reduced mechanical performances, mostly in collapse resistance.
The patent U.S. Pat. No. 7,159,666 of the applicant, offers a solution to improve the collapse resistance, but at the expense of substantial complications in the installation and without taking advantage of the complete steel section.
An advantageous solution is by winding the continuous tubular member on spools to allow to store the pipes in continuous length. This solution allows pipe transportation of continuous length saving assembling time on location.
However, beyond a certain pipe diameter, the dimensions of the necessary spool to store the pipe become prohibitive, as well as the necessary equipment for its unwinding. For instance, on offshore laying vessels, the size of the spool is such that it has to be part of the vessel and the pipe must be wound from a shore construction site close to the laying location. In well casing, the road size constraints and the requirements to locate big size spool on rigs make this solution less attractive if not impossible.
The patent U.S. Pat. No. 3,104,703 of Rike and al offers a solution to reduce the spool size by flattening the tubular lengthwise to reduce the spool diameter. The patent U.S. Pat. No. 5,794,702 of the applicant offers also a longitudinal folding of the tubular which also reduces its radial dimensions making easier to lower it into the well. The patent U.S. Pat. No. 8,069,900 of the applicant offers an improvement in enhancing the collapse resistance of the tubular by creating a composite wall.